ATP-dependent decay and recovery of K+ channels in guinea pig cardiac myocytes.
ATP-dependent decay and recovery of the inward rectifier and ATP-sensitive K+ channels were investigated using inside-out patch recording in cardiac myocytes. The solution facing the inner side of the membrane was instantaneously changed with the oil-gate concentration jump method. Both channels were decayed by removing ATP and were recovered by reapplying ATP. The coexistence of Mg2+ was required for the recovery. 5'-Adenylylimidodiphosphate failed to reverse the ATP-dependent decay. The cumulative histograms of survival time and recovery time, obtained from the inward rectifier K+ channel, showed a single exponential distribution, time constants of which were 55 and 43 s, respectively. The time-dependent nature of decay and recovery was also confirmed in the ATP-sensitive K+ channel. The findings indicated that intracellular ATP is one of the factors that determines the activity of the K+ channels. It is most probable that phosphorylation of channel molecules is essential for maintaining the K+ channel in an operative state.
Takano
M
M
Department of Physiology, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Qin
D Y
DY
Noma
A
A
D000255:Adenosine Triphosphate / Q000502:physiology*; D000266:Adenylyl Imidodiphosphate / Q000494:pharmacology; D000818:Animals; D006168:Guinea Pigs; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors
D015221:Potassium Channels; D000266:Adenylyl Imidodiphosphate; D000255:Adenosine Triphosphate; D008274:Magnesium